1. Field of Invention
This invention relates, generally, to truss assembly tables and, more particularly, to truss assembly tables having stop members for positioning truss planks.
2. Background Art
Wooden trusses are support structures used in the construction of roofs and floors of buildings. Typically, wooden trusses comprise a series of lumber planks arranged in a triangular pattern. The particular design of the wooden truss varies depending on the design and size of the building in which they are used. However, the construction of a single building commonly requires several trusses of the same size.
Wooden trusses are commonly assembled on a series of truss assembly tables that provide a large work surface at a working height above a shop floor. To assemble the truss, the planks are first arranged and secured in the correct configuration on the surface of the table. A pressure roller or hydraulic press then presses attachment plates into adjoining planks thereby fixing the planks in the desired configuration. Chalk lines, measuring tape and other inefficient devices are used to arrange the planks in the proper configuration for the assembly of each truss. Consequently, the task of arranging the planks in the proper configuration is particularly time-consuming.
To hasten the time-consuming task of arranging the planks, locator stops or jigs have been used to indicate the proper placement of planks on the table. The traditional locator stops include pins for attaching the locator stops to the truss table. The traditional truss table has a grid of apertures, which receive the pins of the locator stops. Once the locator stops are properly positioned, the planks are arranged about the stops and the roller or press attaches the planks to one another using an attachment plate. The assembled truss is then removed and the locator stops remain in place to quickly guide the positioning of the planks for the assembly of the remaining identical trusses.
More recent systems have been designed to aid in the quick positioning of truss planks. For instance, one known system has a stop unit having a stop, which rests on the surface of the table and engages the planks. The stop is mounted on a block or clamp member that slides within a C-shaped channel having upper lips level with the table. The channel extends along the length of the truss table, thereby allowing the stop to move to any position along the channel. A measuring scale extends along the top of the channel for indicating the location of the stops.
Another stop locator or jig system includes a jig positioned upon a worm gear located within a C-shaped channel. Rotation of the worm gear causes the jig to translate within the channel to the desired location.
Another exemplary locator stop system includes a pair of locator stops mounted on an oblong jig body. The jig body slides along a rail or ruler, which is attached to the surface of the truss table. The jig body is secured in position by a bolt, which engages apertures in the table.
One locator stop system includes a series of spaced-apart, elongated steel panels supported by a frame. The panels are elevated from the frame by spacing members such that the walls of the spacing members together with the lower surfaces and edges of the panels form a T-shaped channel. The system further includes locator stops, each having a stop portion residing above the panel and a slide portion that slides within the T-shaped channel beneath the lower surface of the panels. The locator stop has a clamping portion between the slide portion and the stop portion that locks the locator stop in position.
Most of these prior locator stops include a base or sliding portion that slides within a C-shaped or T-shaped channel and is located beneath the table or the channel lips. Unfortunately, the sliding base can tilt within the channel making it difficult to smoothly and effectively slide the stop locator to another location within the channel. Also, substantial friction can develop between the sliding base and the channel further hindering the smooth and effective movement of the stop locator. Finally, the prior locator stops are difficult to remove from and install in the channels because the sliding base must be installed beneath the panels or channel lips. Consequently, the prior locator stop must either be disassembled or slid all the way to the end of the channel in order to be removed.
Another locator stop system includes a truss assembly table having a series of elongated, spaced-apart support members supported by a table. The walls of the adjacent support members form a slot. The locating device includes a base that slides within the slot. A bobbin is attached to the top of the base and extends above the surface of the table. The base includes at least one bolt, which is positioned entirely within the channel and is arranged perpendicular to the sidewall of the channel The head of the bolt engages the sidewall of the channel to lock the base in position. However, the head of the bolt may be difficult and cumbersome to access, thus making this system awkward and inefficient.
Although many attempts have been made to improve locator stop systems, a need remains for an effective and efficient locator stop system in which the locator stop can be quickly and easily moved from one position to another along the truss table.